During the press conference following the release, ECB President Mario Draghi said there was a very strong, prevailing consensus on the Governing Council toward an interest rate cut, and within that, there was a prevailing consensus toward a 25 basis-point cut. However, he also made clear that the ECB stands ready to act further if necessary.

The euro area deposit rate was left on hold at 0%, but during the Q&A following the press conference, Draghi said the ECB has an "open mind" toward taking the deposit rate negative in the future, and that the central bank is technically ready to take such action.

These comments about taking the deposit rate negative sent the euro plunging around 100 pips against the U.S. dollar.

With regard to why a rate cut was decided on today when only a few months ago it was viewed as ineffective stimulus, Draghi cited two developments.

The first development that is supposed to make a rate cut more effective today than a few months ago is some easing in recent months of the financial fragmentation that has characterized the euro zone over the past few years.

The second development is that economic weakness has spread to the euro zone's "core economies," making a rate cut more appropriate across the euro zone as opposed to only in the periphery.